1. Field of the Invention
This invention relates to polymeric electrical enclosure having electrical access knockouts integrally molded into the enclosure walls.
2. Background Information
Polymeric electrical enclosures, such as load centers and switches, commonly employ molded knockouts to permit entrance or exit of electrical conductors. These knockouts typically are molded as an integral part of the enclosure. To date, these knockouts have been restricted to having one or two "rings" or segments to accommodate different sizes of electrical conductors, conduits or fittings. The tings are formed by concentric grooves molded into the enclosure wall. A flow leader bridges the grooves to facilitate material flow to the encircled wall portions during the molding process. Examples of polymeric enclosures with such integral knockouts are shown for instance in U.S. Pat. Nos. 4,688,146 and 5,148,348. The enclosure of U.S. Pat. No. 4,688,146 utilizes two diametrically opposite flow leaders aligned with the enclosure mold gate to feed material across two grooves of an integrally molded knockout.
There is a need for an improved polymeric electrical enclosure with integrally molded knockouts which can accommodate a greater range of sizes of conductors, conduits and fittings.
There is also a need for such an improved polymeric electrical enclosure in which the desired size opening in the knockout, especially the smaller sizes, can be easily and reliably selected.
There is also a need for such an improved polymeric electrical enclosure which can be used with snap-in fittings requiring relatively thin wall thicknesses while maintaining the structural and insulative integrity of the enclosure.